CTS V LS6 top end maintenance and upgrades - Need advice to avoid a rabbit hole and or time bomb

So my Gen 1 CTS V has been a good commuter beast for me and has earned a permanent spot in the 84FSP garage.    In the interest of longevity I have some lifter and valve noise that worries me as the motor is a bit of an unknown (LS6 5.7).   I am getting my push-rod education on this, way out of my vw comfort zone.  Any direction on what to do and not do from the hive would be appreciated.

The last dyno numbers were mild at 358hp and 367tq.  The target is nice rowdy but reliable 450+ wheel hp daily which seems pretty easy. 

Maintenance dictates that the heads come off to do lifters.  As it is already apart, I end up looking at what to do for hp and maintenance so I don't end up here again.  I am also trying to to this over a weekend which means picking up spare heads and having all the goodies on hand before we get started.

Horsepower upgrades in the plans

-AR research 226CC milled to 58cc, cnc ported&polished, cnc valve job, upgraded valvesprings keepers fasteners etc 

     - I wanted to do something more like 11:1 and this setup will be ~11.7:1 (up from 10.5:1) 

     - The plan was to reuse the unknown cam after inspection and measuring but not wedded to this

     - Still need to do pushrod measurements and pick those up but won't know till it's going together

     - I hear there is a nice setup to use the 1.8 lS3 rockers but have found conflicting info thus far

-OBX stainless header cat combo $750- should match up nice with the Corsa exhaust already on it 

-LS2 Doorman intake setup ala Rockauto (uses a fast lower and supposedly good for 15hp) 

-42lb LS3 oem takeoff injectors (picked up for $70) stockers are at 97% of duty cycle already

-Update on the speed density tune 

OEM Maintenance items while I'm in there

-Head gasket 0.051

-Valve cover gasket

-Timing chain (ls2 upgrade)

-Timing gear (lS2 upgrade)

-Crankshaft gear inner and outer (LS2 upgrade)

-Timing cover seal

-Timing cover gasket

-Exhaust mani gaskets

-Exhaust mani studs/nuts (cheap insurance?)

-Oil pump (Ls2 upgrade)

 Currently this list of things still to be purchased totals $2300.  It is just amazing how cheap all the oem maintenance items are for these.  I can claw back ~400 for the heads bringing this back to 1900. 

Am I missing anything here?

You need to ditch that cam.  If you're making ~360rwhp with it now, chances are its stock.  It's easy to make 400rwhp, it's hard to make 450rwhp with stock displacement.  I made 425rwhp on my 383 stroker with AR 232 heads, Kooks long tubes and FAST 92/92.  The cam was holding me back, if I'd swapped in one meant for the 383 450rwhp was easily there to be had.

I like the AR heads, Trick Flow 215's are really nice too.  Get a good cam, not a really flat street cam like a 228 or 228R, you'll want something a bit more wild.

I'm a fan of either the FAST 92/92 or the FAST 102/102.  They're worth the money, as are a good set of 1 7/8" long tube headers...

In reply to docwyte :

I agreed that it's being held back currently but I think the culprit is the stock exhaust manifolds and clogged cats.  I was very dissapointed with it's dyno number, especially as this had a stroker setup that i believed to be in the car when bought....  Long story that.

 The CTS V manifolds were notoriously bad costing the LS6 10hp or so vs the Z06.  I'm guessing the cats are clogged as it was running pig rich when I bought it.

It has a very healthy lope and is running a speed density tune that is fresh.  We're guessing the current cam is ~500 lift.  

Given how much that head setup will flow you are likely right that it will need a wild cam to get the most from it.  I need to do more homework there but wanted to get some direction before start spending more money.

Headers are a definite and I'm currently messing with the Doorman LS2 intake setup that is supposed to be a healthy upgrade.  It gained 75% of the fast setups for a lot less money, no question that they are better but not 3x better from my side.

It's more work, but I recommend an Improved Racing oil pan baffle.

(never had one on my CTS-V, but I have one on my 99 Z28)

I guess the best thing to do would be to pull the cam and measure it, so you know exactly what you have.  Stock manifolds aren't going to choke 40rwhp out of that engine.  Maybe if the cats were totally clogged, but then the engine would hardly run.

360rwhp is what a stock LS6 makes, thats what makes me thing that cam is stock...

I didn't think the heads needed to be removed to change the lifters or replace the cam on these motors.  I may be wrong, though.  

I’ll have a buddy pull the all data to see if this can be done without pulling heads.  Scope of work will shrink dramatically if that’s the case.  

The compression from the shaved heads I was ready to pickup have my tuner nervous about their use for pump gas.  I need to do more research on deck height and piston to valve relief.  My calculations from a web tool show the stock 0.051 gasket leaving me at 11.7:1.  I believe I can use a truck gasket and get it to 11.25:1 which I thought would be kosher.   The tuner disagreed and thought nothing higher than 10.8:1.  I’m at a loss on that one as there many folks running 11:1 and higher static compression.

Cam will be coming out to get measured regardless.

The cam can be replaced on an LS engine with the heads in place.  With the pushrods out, rotate the cam to push the lifters up and they will stay in place, allowing the cam to come out.

The heads have to come off to change the lifters.   Roller lifters + the anti-rotation hardware are much taller than old flat tappets so there is simply not enough clearance under the heads for lifter removal.  On the plus side the pushrods are quite short, limiting flex.

In reply to GreenVWs :

Ah thanks sir - was thinking that was the case but would have loved to avoid  it.  

You can definitely swap the cam without pulling the heads.  I thought you could swap the lifters too, with a little trickery but I have to confess that I've never done it.  

11:1 compression ratio will be fine as long as you always run premium, you just don't have much leeway for bad gas/knock events.